Sunshine makes you stronger.

That’s the opposite message we’ve been given for years—years spent avoiding the sun whenever possible, covering every bit of exposed skin, and slathering ourselves with sunblock.  But an ever-growing body of evidence proves that what sunshine gives us lowers our risk for many cancers, chronic conditions, mental health issues and, yes, the seasonal respiratory illnesses.

If you’re in a hurry, here’s your takeaway: Aside from the fact winter is too cold in many places for exposed skin, winter sunlight north of the equator is too low in the sky to trigger the body to produce its own Vitamin D.  Repeatedly, research has shown that steady intake of Vitamin D3 –NOT sporadic mega-doses! — makes folks less susceptible to seasonal illnesses, helps curb “the winter blues,” and reduces the incidence of many cancers.

The easiest and cheapest way to fix the problem is a high-quality Vitamin D3 supplement of at least 2000IU daily.  (This elderberry/D3 combination is my favorite, and this is the one my little nephews take.)  Basically, for as little a dime or two a day, you can be healthier and happier all year long.

If you want to know how and why, read on!

First of all, Vitamin D isn’t really a vitamin.  It’s a hormone produced via sun exposure to the skin, and it affects every aspect of our health from how well we sleep to how well we destroy abnormal cells.  Every system in the body requires D to function properly, which explains why so many conditions are linked to low levels (not necessarily “clinical” deficiency) of D.

A few years ago, researchers in Japan looked at the impact of daily D supplementation on the health of school children.  Within two months, the incidence of flu among those taking D was around 40% lower than in the control group.  A meta-analysis of other studies also found a reduction in the incidence of flu among those taking D, and an examination of health data found a similar impact on upper respiratory infections.  And if you’re looking for a great deal of reading material related to the connection between D and respiratory conditions, check out this review and its links from the European Journal of Allergy and Clinical Immunology.

Alas, many of the recent cold/flu-specific studies that claim there’s no connection have used ridiculously low amounts (400IU daily) or ridiculously high single doses (100000IU monthly).  Since research showing positive outcomes has used daily doses ranging from 1200IU to 4000IU, I’m not certain why so many researchers are determined to use wild different doses while at the same time either shouting more research is needed to confirm successful findings, or dismissing successful findings altogether.  That’s just silliness.

But let’s say you’re not convinced D will have any impact on whether you come down with the seasonal health.  Allow me show you a few other things that might make D worth your time and dimes.

How about a review of global literature on the connection between D and cancer that concludes tens of thousands of cases could be prevented with proper D levels?

How about improving digestive health, and even reducing the incidence and effects of Crohn’s?

How about research showing a 10% increase in the body’s D level corresponds to an 8% decrease in high blood pressure risk?

Then there’s the research showing low D levels cause systemic inflammation (explaining why low D is linked to rheumatoid arthritis and heart disease), that raising D levels improves glucose control in diabetics, and that low levels are associated with depression?

That’s plenty of indicators for me.  I’m hoping it’ll be enough for you as well.